Atomic Structure Flashcards
When was dalton’s theory about the structure of an atom
Early 1800s
Describe daltons theory
All elements are made up of small indivisible particles called atoms
Atoms can not be created or destroyed
Atoms of different elements have different properties
When atoms combine they form molecules or compounds
Believed that atoms were indestructible and varied in shape and size.
Who and when did the plum pudding model come about
1897 j.j. Thomson
What did j.j. Thomson discover
He discovered the electron that forced daltons theory to shift slightly
Explain what Thomson proposed about plum pudding
JJ Thompson proposed the plum pudding model which stated that the negative electrons were embedded in a positive sphere like raisins in a plum pudding
How did Ernest Rutherford alter Thomson model
In 1911 Ernest Rutherford revised JJ Thompson’s model to the model which has electrons orbiting a positive nucleus
What lead to todays model of the atom
In 1932 James Chadwick discovered the neutron which led to the days model of a central nucleus containing positive protons and neutral charge neutrons with negative charged electrons orbiting around the nucleus in shells.
Who proposed the idea that matter is composed of small indivisible particles called atoms
Greek philosophers Democritus and leucippis
What ideas did Aristotle propose
He believed that matter was composed of the four elements, air earth fire and water and use these ideas to explain matters and its behaviour. This significantly delayed the development of the atomic theory
When did dalton publish the first atomic theory
1808
How did Thomson discover the electron
He was investigating the way gases conduct electricity. he showed that electrons had the negative charge by showing that electrons that were admitted from the negative terminal were attracted to the positive terminal therefore making them negative(opposites attract )
Why did Thomson consider the atom neutral
As it contain an equal numbers of positive and negative charges that cancelled each other
Where is virtually all of the atoms mass contained?
Nucleus
How did Rutherford model relate to planets around the son
The same way planets revolve around the Sun electrons revolve around the positive mucus
Describe simply the structure of an atom
An atom is composed of a small dense positively charged nucleus at the centre (composed of protons and neutrons) with negatively charge electrons in shells (energy levels)orbiting the nucleus
What is the relative mass, relative charge and position of;
Proton
Neutron
Electron
Proton=1,+1 and nucleus
Neutron=1,0 and nucleus
Electron=1/1840, -1 and shells
What something radius of an atom
About 0.1nm(1x10 to the power of -10m)
What size is the nucleus in relevance to the rest of the atom
The nucleus is less than 1/10,000th of that of the atom(less than 1x10 to the power of -14m)
1nm
1x10 to the power of -9
(0.000000001)
Atomic number
This is the number of protons in(the nucleus) an atom
Mass number
This is the total number of protons and neutrons in(the nucleus of)an atom
Top number on the periodic table
How, do the atoms of one element differ from those of another?
The number of protons, neutrons and electrons found in each atom are different. Each element had a unique atomic number
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Element
Is a substance that consists of only one type of atom and it cannot be broken down into anything simpler by chemical means
How can we work all the number of electrons in an atom
As an atom is electronically neutral then the number of protons must be equal to the number of electrons so we look at the atomic number to find how many electrons are in an elemt
